
Oncol Res Treat 2024;47(suppl 1):7–283 Abstracts220
305
Unraveling causes of drug resistance in BRAFV600ECRC using
single-cell mRNA sequencing of preclinical models
Anna Kotarac1,2,3,4; Lara Kunhardt von Schmidt1,4; Alexander Malt5;
Alexandra Trinks6; Hiroki Osumi7; Annalisa Lorenzato8;
Federica DI Nicolantonio8,9; Mariangela Russo8; Ryoji Yao10;
Naveed Ishaque5; Markus Morkel2,3,11,12; Alberto Bardelli8,13;
Ulrich Keilholz1,2,3; Christine Sers2,3,12; Sebastian Stintzing2,3,4;
Loredana Vecchione1,2,3,4,14
1Charité Comprehensive Cancer Center, Berlin, Deutschland
2German Cancer Consortium, Berlin, Deutschland
3German Cancer Research Center, Heidelberg, Deutschland
4Department of Hematology, Oncology, and Cancer Immunology, Campus
Charité Mitte, Charité Universitätsmedizin Berlin, Berlin, Deutschland
5BIH Center for Digital Health, Computational Oncology, Berlin Institute of
Health (BIH), Berlin, Deutschland
6Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Bioportal Single
Cells, Berlin, Deutschland
7Department of Gastroenterological Chemotherapy, Cancer Institute Hospital,
Japanese Foundation for Cancer Research, Tokyo, Japan
8Department of Oncology, University of Turin, Turin, Italien
9Candiolo Cancer Institute, FPO-IRCCS, Candiolo, Italien
10Department of Cell Biology, Cancer Institute, Japanese Foundation for Cancer
Research, Tokyo, Japan
11Berlin Institute of Health at Charité Universitätsmedizin Berlin, Bioportal Single
Cells, Berlin, Deutschland
12Department of Pathology, Charité Universitätsmedizin Berlin, Berlin,
Deutschland
13IFOM ETS, The AIRC Institute of Molecular Oncology, Milan, Italien
14Berlin Institute of Health at Charité Universitätsmedizin Berlin,BIH Biomedical
Innovation Academy, BIH Charité (Junior) (Digital) Clinician Scientist Program,
Berlin, Deutschland
Background: Chemotherapy remains the mainstay of palliative treat-
ments for BRAFV600E metastatic colorectal cancer, with limited ecacy
(1). Despite the approval of a new chemo-free regimen aer systematic
therapy, response is still poor, thus highlighting an unmet clinical need
(2,3). erefore, we aim to use single-cell mRNA sequencing (scRNAseq)
to identify transcriptional subpopulations as biomarkers of resistance to
conventional therapy.
Methods: Nine BRAFV600E CRC cell lines and ten BRAFV600E CRC
patient-derived organoids (PDOs) are being treated with the following
drugs in short term proliferation assays: erlotinib (OSI-744), encorafenib
(LGX818), 5-urouracil (5-FU), irinotecan (SN-38), oxaliplatin (L-OHP),
OSI-744+LGX818, OSI-744+SN-38, 5-FU+SN-38, 5-FU+L-OHP,
5-FU+SN-38+L-OHP. Sensitivity is being dened by IC50, AUC and
Synergy Score. Aer isolation, cell lines and PDOs at baseline and aer
treatment are being subjected to barcoding, library preparation and
sequencing (Illumina NovaSeq, 1600 mio. reads per library).
Results: Four out of ten PDO models are sensitive to OSI-744+LGX818
and one out of ten is sensitive to SN38+OSI-744. While HT29 CRC cell
line is resistant to OSI-744+LGX818, 5-FU+L-OHP, 5-FU+SN-38 and
5-FU+SN-38+L-OHP, KM20 and WiDr CRC cell lines are sensitive
to these combinations. Further drug testing in remaining models and
scRNAseq is currently ongoing. e integration of response data and
scRNAseq analysis will be validated in publicly available and in-house
clinical data sets.
Discussion: So far variable responses to drug testing have been observed.
ScRNAseq will help to identify genomic determinants of BRAFV600E heter-
ogeneity and resistance to conventional therapies.
Conclusion: To the best of our knowledge, this is the rst preclinical study
using BRAFV600E CRC preclinical models, aiming at identifying mecha-
nisms of resistance to conventional treatment currently used in clinical
practice by scRNAseq technology.
1 Kuipers et al., PMID: 27189416.
2 Tabernero et al., PMID: 33503393.
3 Middleton et al., PMID: 32047001.
Disclosure Statement: e authors declare the following: LV received research
funding and travel bursaries from Pierre Fabre.
311
German Radiation Oncology‘s Next Generation: A web-based
Survey of Young Biologists, Medical Physicists, and Physicians
Lisa Deloch1,2,3,4; Thomas Weissmann1,3,4; Johann Matschke5;
Sarah Stefanowicz4,6; Maximilian Grohmann4,7; Felix Ehret4,8;
Alexander Fabian4,9; Alexander Rühle4,10,11; Simone Wegen4,12;
Sebastian Lettmaier1,3; Maike Trommer4,13,14; Elena Sperk15;
Annemarie Schröder4,16
1Department of Radiation Oncology, Universitätsklinikum Erlangen,
Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Deutschland
2Translational Radiationbiology, Department of Radiation Oncology,
Universitätsklinikum Erlangen, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Erlangen, Deutschland
3Comprehensive Cancer Center Erlangen-EMN, Erlangen, Deutschland
4Young DEGRO Trial Group, Berlin, Deutschland
5Institute of Cell Biology (Cancer Research), University Hospital Essen, University
of Duisburg-Essen, Essen, Deutschland
6Department of Radiation Oncology, Klinikum rechts der Isar, Technical
University of Munich (TUM), München, Deutschland
7Department of Radiotherapy and Radiation Oncology, University Medical
Center Hamburg-Eppendorf, Hamburg, Deutschland
8Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität
Berlin and Humboldt-Universität zu Berlin, Department of Radiation Oncology,
Berlin, Deutschland
9Klinik für Strahlentherapie, Universitätsklinikum Schleswig-Holstein, Kiel,
Deutschland
10Department of Radiation Oncology, University of Freiburg – Medical Center,
Freiburg, Deutschland
11Department of Radiation Oncology, University of Leipzig, Leipzig, Deutschland
12Department of Radiation Oncology, Cyberknife and Radiotherapy, Faculty of
Medicine and University Hospital Cologne, Köln, Deutschland
13Department of Radiation Oncology, University of Cologne, Faculty of Medicine
and University Hospital Cologne, Köln, Deutschland
14Department of Radiation Oncology, Olivia Newton-John Cancer Wellness &
Research Centre, Austin Health, Melbourne, VIC, Melbourne, Australien
15Mannheim Cancer Center, Universitätsmedizin Mannheim, Medizinische
Fakultät Mannheim, Universität Heidelberg, Mannheim, Deutschland
16Department of Radiotherapy and Radiation Oncology, University Medical
Center Rostock, Rostock, Deutschland
Background: e eld of radiation oncology (RO) is a close interconnec-
tion of multiple disciplines and has undergone a signicant change due to
new diagnostic and therapeutic developments that have revolutionized the
eld. A close, constructive collaboration of physicians, medical physicists,
and biologists is required to ensure existing and future-oriented standards.
However, during day-to-day work, the impression of a negative trend within
the workforce in RO arises, as young scientists seem to leave the eld quickly
despite active oers for career support from the (young) German scientic
organizations. Reasons for a career change may be multifactorial. We thus
aim to capture the current situation of all scientic disciplines in RO as we
intend to not only gain insight into the needs and problems of young scien-
tists but also to identify measures that can be taken for a positive turnaround
to foster a future-oriented and high-quality scientic culture in Germany.
Methods: Over a period of 6 weeks, a web-based survey was conducted
by the Trial Group from the youngDEGRO (Deutsche Gesellscha für
Radioonkologie) with members of the yDeGBS (Deutsche Gesellscha
für Biologische Strahlenforschung) and yMP (Deutsche Gesellscha für
Medizinische Physik) which included 13 generalized and 20-25 occupa-
tion-specic questions.
Results: e 218 questionnaires were completed by 89 physicians, 59 biol-
ogists, and 70 physicists. While overall satisfaction in the workforce seems
to be rather high, and the majority of participants would choose the same
career path again, several factors contribute to a decline in employee satis-
faction. Although university hospitals appear to be an attractive employer,
factors such as assurance of protected research time, especially for physi-
cians, will have to be addressed.
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